1 files changed, 134 insertions, 0 deletions
diff --git a/jstests/replsets/write_concern_after_stepdown_and_stepup.js b/jstests/replsets/write_concern_after_stepdown_and_stepup.js
new file mode 100644
index 00000000000..ea1c6312eae
--- /dev/null
+++ b/jstests/replsets/write_concern_after_stepdown_and_stepup.js
@@ -0,0 +1,134 @@
+/*
+ * Tests that heartbeats containing writes from a different branch of history can't cause a stale
+ * primary to incorrectly acknowledge a w:majority write that's about to be rolled back, even if the
+ * stale primary is re-elected primary before waiting for the write concern acknowledgement.
+ */
+(function() {
+    'use strict';
+
+    var name = "writeConcernStepDownAndBackUp";
+    var dbName = "wMajorityCheck";
+    var collName = "stepdownAndBackUp";
+
+    var rst = new ReplSetTest({
+        name: name,
+        nodes: [
+            {},
+            {},
+            {rsConfig: {priority: 0}},
+        ],
+        useBridge: true
+    });
+    var nodes = rst.startSet();
+    rst.initiate();
+
+    function waitForState(node, state) {
+        assert.soonNoExcept(function() {
+            assert.commandWorked(node.adminCommand(
+                {replSetTest: 1, waitForMemberState: state, timeoutMillis: rst.kDefaultTimeoutMS}));
+            return true;
+        });
+    }
+
+    function waitForPrimary(node) {
+        assert.soon(function() {
+            return node.adminCommand('ismaster').ismaster;
+        });
+    }
+
+    function stepUp(node) {
+        var primary = rst.getPrimary();
+        if (primary != node) {
+            assert.throws(function() {
+                primary.adminCommand({replSetStepDown: 60 * 5});
+            });
+        }
+        waitForPrimary(node);
+    }
+
+    jsTestLog("Make sure node 0 is primary.");
+    stepUp(nodes[0]);
+    var primary = rst.getPrimary();
+    var secondaries = rst.getSecondaries();
+    assert.eq(nodes[0], primary);
+    // Wait for all data bearing nodes to get up to date.
+    assert.writeOK(nodes[0].getDB(dbName).getCollection(collName).insert(
+        {a: 1}, {writeConcern: {w: 3, wtimeout: rst.kDefaultTimeoutMS}}));
+
+    // Stop the secondaries from replicating.
+    secondaries.forEach(function(node) {
+        assert.commandWorked(
+            node.adminCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'alwaysOn'}));
+    });
+    // Stop the primary from calling into awaitReplication()
+    assert.commandWorked(nodes[0].adminCommand(
+        {configureFailPoint: 'hangBeforeWaitingForWriteConcern', mode: 'alwaysOn'}));
+
+    jsTestLog("Do w:majority write that won't enter awaitReplication() until after the primary " +
+              "has stepped down and back up");
+    var doMajorityWrite = function() {
+        // Run ismaster command with 'hangUpOnStepDown' set to false to mark this connection as
+        // one that shouldn't be closed when the node steps down.  This simulates the scenario where
+        // the write was coming from a mongos.
+        assert.commandWorked(db.adminCommand({ismaster: 1, hangUpOnStepDown: false}));
+
+        var res = db.getSiblingDB('wMajorityCheck').stepdownAndBackUp.insert({a: 2}, {
+            writeConcern: {w: 'majority'}
+        });
+        assert.writeErrorWithCode(res, ErrorCodes.PrimarySteppedDown);
+    };
+
+    var joinMajorityWriter = startParallelShell(doMajorityWrite, nodes[0].port);
+
+    jsTest.log("Disconnect primary from all secondaries");
+    nodes[0].disconnect(nodes[1]);
+    nodes[0].disconnect(nodes[2]);
+
+    jsTest.log("Wait for a new primary to be elected");
+    // Allow the secondaries to replicate again.
+    secondaries.forEach(function(node) {
+        assert.commandWorked(
+            node.adminCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'off'}));
+    });
+
+    waitForPrimary(nodes[1]);
+
+    jsTest.log("Do a write to the new primary");
+    assert.writeOK(nodes[1].getDB(dbName).getCollection(collName).insert(
+        {a: 3}, {writeConcern: {w: 2, wtimeout: rst.kDefaultTimeoutMS}}));
+
+    jsTest.log("Reconnect the old primary to the rest of the nodes");
+    nodes[0].reconnect(nodes[1]);
+    nodes[0].reconnect(nodes[2]);
+
+    jsTest.log("Wait for the old primary to step down, roll back its write, and apply the " +
+               "new writes from the new primary");
+    waitForState(nodes[0], ReplSetTest.State.SECONDARY);
+    rst.awaitReplication();
+
+    // At this point all 3 nodes should have the same data
+    assert.soonNoExcept(function() {
+        nodes.forEach(function(node) {
+            assert.eq(null,
+                      node.getDB(dbName).getCollection(collName).findOne({a: 2}),
+                      "Node " + node.host + " contained op that should have been rolled back");
+            assert.neq(null,
+                       node.getDB(dbName).getCollection(collName).findOne({a: 3}),
+                       "Node " + node.host +
+                           " was missing op from branch of history that should have persisted");
+        });
+        return true;
+    });
+
+    jsTest.log("Make the original primary become primary once again");
+    stepUp(nodes[0]);
+
+    jsTest.log("Unblock the thread waiting for replication of the now rolled-back write, ensure " +
+               "that the write concern failed");
+    assert.commandWorked(nodes[0].adminCommand(
+        {configureFailPoint: 'hangBeforeWaitingForWriteConcern', mode: 'off'}));
+
+    joinMajorityWriter();
+
+    rst.stopSet();
+}());